Insertion slots along deterministic track for movable network device in a deterministic network

ABSTRACT

In one embodiment, a method comprises determining a movable network device is moving along a repeatable sequence of access point devices in a deterministic network; and establishing a deterministic track along the repeatable sequence of access point devices, the deterministic track comprising insertion slots allocated for insertion of a data packet, by the movable network device, into the deterministic track via any one of the respective access point devices.

This application is a continuation of application Ser. No. 16/107,759,filed Aug. 21, 2018, which is a continuation of application Ser. No.15/055,690, filed Feb. 29, 2016.

TECHNICAL FIELD

The present disclosure generally relates to generation of insertionslots along a deterministic track for a movable network device in adeterministic network.

BACKGROUND

This section describes approaches that could be employed, but are notnecessarily approaches that have been previously conceived or employed.Hence, unless explicitly specified otherwise, any approaches describedin this section are not prior art to the claims in this application, andany approaches described in this section are not admitted to be priorart by inclusion in this section.

The Internet Engineering Task Force (IETF) is attempting to proposestandards that can be applied to wireless devices for the stringentrequirements of deterministic networks (e.g., minimal jitter, lowlatency, minimal packet loss). For example, Low power and Lossy Networks(LLNs) allow a large number (e.g., tens of thousands) ofresource-constrained devices to be interconnected to form a wirelessmesh network. The IETF has proposed a routing protocol (“6TiSCH”) thatprovides IPv6 routing using time slotted channel hopping (TSCH) based onIEEE 802.15.4e, enabling LLN devices to use low-power operation andchannel hopping for higher reliability. Routes can be based on therouting protocol for LLNs (RPL).

The 6TiSCH architecture specifies a Channel distribution/usage (CDU)matrix of “cells”, each cell representing a unique wireless channel at aunique timeslot. The CDU is partitioned into prescribed “chunks”, eachchunk comprising multiple cells distributed in time and frequency (i.e.,a different channel each timeslot). The 6TiSCH architecture specifiesthat a RPL parent device can allocate cells within an appropriated chunkto its first-hop child devices within its interference domain.

The 6TiSCH architecture also specifies that a central path computationelement (PCE) can compute and install a track allocating a sequence ofcells for each hop along a path from a source to a destination.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the attached drawings, wherein elements having thesame reference numeral designations represent like elements throughoutand wherein:

FIG. 1 illustrates an example system having an apparatus forestablishing a deterministic track along a repeatable sequence of accesspoint devices, with insertion slots for insertion of a data packet by amovable network device, according to an example embodiment.

FIG. 2 illustrates another example system having one or more apparatusfor establishing a deterministic track along a repeatable sequence ofaccess point devices, with insertion slots for insertion of a datapacket by a movable network device, according to an example embodiment.

FIG. 3 illustrates an example implementation of any one of the devicesof FIG. 1 or 2.

FIG. 4 illustrates an example method of establishing a deterministictrack with insertion slots for insertion of a data packet, by a movablenetwork device, along a repeatable sequence of access point devices,according to an example embodiment.

FIG. 5 illustrates in further detail an example method for establishingthe deterministic track along a repeatable sequence of access pointdevices, with insertion slots for insertion of a data packet by amovable network device, according to an example embodiment.

FIGS. 6A, 6B, and 6C illustrate an example sequence of a movable networkdevice establishing a deterministic track along the repeatable sequenceof access point devices, based on successively obtaining insertion slotsfrom each of the access point devices, according to an exampleembodiment.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

In one embodiment, a method comprises determining a movable networkdevice is moving along a repeatable sequence of access point devices ina deterministic network; and establishing a deterministic track alongthe repeatable sequence of access point devices, the deterministic trackcomprising insertion slots allocated for insertion of a data packet, bythe movable network device, into the deterministic track via any one ofthe respective access point devices.

In another embodiment, an apparatus comprises a processor circuit and adevice interface circuit. The processor circuit is configured fordetermining a movable network device is moving along a repeatablesequence of access point devices in a deterministic network. Theprocessor circuit further is configured for establishing a deterministictrack along the repeatable sequence of access point devices, thedeterministic track comprising insertion slots allocated for insertionof a data packet by the movable network device into the deterministictrack via any one of the respective access point devices. The deviceinterface circuit configured for causing the movable network device toinsert the data packet into the deterministic track based on any one ofthe insertion slots for the respective access point devices.

In another embodiment, one or more non-transitory tangible media isencoded with logic for execution by a machine and when executed by themachine operable for: determining a movable network device is movingalong a repeatable sequence of access point devices in a deterministicnetwork; and establishing a deterministic track along the repeatablesequence of access point devices, the deterministic track comprisinginsertion slots allocated for insertion of a data packet, by the movablenetwork device, into the deterministic track via any one of therespective access point devices.

In another embodiment, a method comprises: a movable network devicedetermining a nearest access point device as the movable network devicemoves along a repeatable sequence of access point devices of adeterministic network; the movable network device transmitting a datapacket to the nearest access point device based on selecting aninsertion slot associated with the nearest access point device, fromamong a plurality of insertion slots associated with the respectiveaccess point devices according to a deterministic track, fordeterministic forwarding of the data packet within the sequence ofaccess point devices.

In another embodiment, an apparatus comprises a processor circuit and adevice interface circuit. The processor circuit is configured fordetermining a nearest access point device as the apparatus, implementedas a movable network device, moves along a repeatable sequence of accesspoint devices of a deterministic network. The processor circuit furtheris configured for selecting an insertion slot associated with thenearest access point from among a plurality of insertion slotsassociated with the respective access point devices according to adeterministic track. The device interface circuit is configured fortransmitting a data packet to the nearest access point device using theselected insertion slot, for deterministic forwarding of the data packetwithin the sequence of access point devices.

In another embodiment, one or more non-transitory tangible media isencoded with logic for execution by a machine and when executed by themachine operable for: the machine, implemented as a movable networkdevice, determining a nearest access point device as the movable networkdevice moves along a repeatable sequence of access point devices of adeterministic network; the movable network device transmitting a datapacket to the nearest access point device based on selecting aninsertion slot associated with the nearest access point device, fromamong a plurality of insertion slots associated with the respectiveaccess point devices according to a deterministic track, fordeterministic forwarding of the data packet within the sequence ofaccess point devices.

In another embodiment, a method comprises: an access point device in adeterministic network receiving identification of a first insertion slotallocated exclusively for transmission of a data packet originated by amovable network device to a successor access point device, the accesspoint device and the successor access point device belonging to arepeatable sequence of access point devices followed by the movablenetwork device as the movable network device moves in the deterministicnetwork; the access point device identifying a second insertion slotallocated to the movable network device and preceding the firstinsertion slot; the access point device receiving, during the secondinsertion slot, a data packet originated by the movable network device;and the access point device deterministically forwarding the datapacket, received during the second insertion slot, to the successoraccess point device at the first insertion slot, the second insertionslot preceding the first insertion slot being part of a deterministictrack established for deterministic forwarding of the data packet alongthe sequence of access point devices.

In another embodiment, an apparatus comprises a device interface circuitand a processor circuit. The device interface circuit is configured forreceiving, in a deterministic network, identification of a firstinsertion slot allocated exclusively for transmission of a data packetoriginated by a movable network device to a successor access pointdevice. The apparatus implemented as an access point device in thedeterministic network, the access point device and the successor accesspoint device belonging to a repeatable sequence of access point devicesfollowed by the movable network device as the movable network devicemoves in the deterministic network. The processor circuit is configuredfor identifying a second insertion slot allocated to the movable networkdevice and preceding the first insertion slot. The device interfacecircuit is configured for receiving, during the second insertion slot, adata packet originated by the movable network device. The deviceinterface circuit further is configured for deterministically forwardingthe data packet, received during the second insertion slot, to thesuccessor access point device at the first insertion slot, the secondinsertion slot preceding the first insertion slot being part of adeterministic track established for deterministic forwarding of the datapacket along the sequence of access point devices.

In another embodiment, one or more non-transitory tangible media isencoded with logic for execution by a machine and when executed by themachine operable for: the machine, implemented as an access point devicein a deterministic network, receiving identification of a firstinsertion slot allocated exclusively for transmission of a data packetoriginated by a movable network device to a successor access pointdevice, the access point device and the successor access point devicebelonging to a repeatable sequence of access point devices followed bythe movable network device as the movable network device moves in thedeterministic network; the access point device identifying a secondinsertion slot allocated to the movable network device and preceding thefirst insertion slot; the access point device receiving, during thesecond insertion slot, a data packet originated by the movable networkdevice; and the access point device deterministically forwarding thedata packet, received during the second insertion slot, to the successoraccess point device at the first insertion slot, the second insertionslot preceding the first insertion slot being part of a deterministictrack established for deterministic forwarding of the data packet alongthe sequence of access point devices.

DETAILED DESCRIPTION

FIG. 1 illustrates an example system 10 that enables establishment of adeterministic track 12 for deterministic forwarding of a data packet 14originated by a movable wireless network device 16 that moves along aphysical path 18 overlying a repeatable sequence of wireless accesspoint devices 20, according to an example embodiment. The deterministictrack 12 includes insertion slots 22 allocated for insertion of the datapacket 14 into the deterministic track 12 via any one of the respectiveaccess point devices 20.

Conventional implementations of a deterministic track (e.g., GeneralizedMulti-protocol Label Switching (G-MPLS) according to the 6TiSCHarchitecture) in a deterministic network assume that a central pathcomputation element (PCE) computes and installs the deterministic trackalong a fixed path of next-hop nodes between a fixed source device and afixed destination device. In other words, the deterministic track isconstructed based on the assumption that the source network device isfixed and does not move; hence, if a source network device is movable(e.g., a mobile node or mobile network device) and thus detaches from afirst access point device and attaches to a second (different) accesspoint device, the PCE would need to recalculate an updated deterministictrack providing for the movable network device a deterministic path forreaching a destination device via the second access point device.

According to example embodiments, a deterministic track 12 isestablished based on the movable network device “J” 16 moving along arepeatable sequence of access point devices 20 in the deterministicnetwork 10. The repeatable sequence (e.g., “E”-“D”-“C”-“B”-“A”) enableseach access point device (e.g., “D” 20 d) in the repeatable sequence tohave an associated insertion slot (e.g., 22 d) reserved exclusively fortransmission of a data packet 14, originated by the movable networkdevice 16, to the corresponding access point device (e.g., “D” 20 d).The insertion slot 22, also referred to as a “dual entry” insertionslot, enables the data packet 14 to be received by the access pointdevice (e.g., “D” 20 d) either from the movable network device 16, orfrom a successive next-hop second access point (e.g., “E” 20 e) havingreceived the data packet via its own corresponding “dual entry”insertion slot (e.g., 22 e).

Hence, the concatenated sequence of “dual entry” insertion slots 22 e,22 d, 22 c, 22 b, and 22 a from the repeatable sequence of access pointdevices “E”-“D”-“C”-“B”-“A” establishes a deterministic track 12 thatenables the movable network device 16 to insert the data packet 14 intoany one of the access point devices “E”, “D”, “C”, “B”, or “A” 20 as themovable network device “J” 16 moves along the physical path 18. Asillustrated in FIG. 1, each of the insertion slots 22 a, 22 b, 22 c, 22d, and 22 e are allocated from a CDU matrix 24 having a plurality ofcells 26, each cell 26 representing a unique wireless channel at aunique timeslot. Hence, each insertion slot 22 corresponds to a uniquecell 26. The CDU matrix 24 can be generated by a PCE 28. The repeatableCDU matrix 24 is illustrated as encompassing sixteen (16) frequencychannel offsets over thirty-one (31) 10 millisecond (ms) timeslots, suchthat the CDU matrix 24 has a total duration of 310 ms.

Hence, the data packet 14 is propagated throughout the deterministictrack 12 within a single instance of the repeatable CDU matrix 24,regardless of the access point device 20 that receives the data packet14 from the movable network device “J” 16. As illustrated in FIG. 1, therepeatable sequence of access point devices “E”-“D”-“C”-“B”-“A” startsat a first end with a first (e.g., “A” 20 a) of the access pointdevices, positioned as an origin of the repeatable sequence of accesspoint devices: the first access point device “A” 20 a is allocated thelatest insertion slot 22 a (in time) relative to the other access pointdevices 20 b, 20 c, 20 d, and 20 e successively following the firstaccess point device “A” 20 a in the repeatable sequence.

The term “successor” access point device refers to an access pointdevice (e.g., “B” 20 b) that is “ahead” of a second next-hop accesspoint device (e.g., “C” 20 c) that “successively follows” (i.e.,succeeding) the successor access point device; in other words, an accesspoint device (e.g., “C” 20 c) receiving a data packet 14 will forwardthe data packet 14 to its successor access point device (e.g., “B” 20 b)for deterministic propagation of the data packet toward its destinationdevice 30. The deterministic track 12 is established based on thesucceeding access point device (e.g., “C” 20 c) having an insertion slot(e.g., 22 c) that precedes in time the corresponding insertion slot(e.g., 22 b) of its successor access point device (e.g., “B” 20 b),enabling the successor access point device (e.g., “B” 20 b) to receivethe data packet from its succeeding next-hop neighbor (e.g., “C” 20 c)before the insertion slot (e.g., 22 b) of the successor access pointdevice (e.g., “B” 20 b).

As illustrated in FIG. 1 the access point device “B” 20 b successivelyfollowing the first access point device “A” 20 a in the repeatablesequence is allocated an insertion slot 22 b preceding the insertionslot 22 a in the CDU matrix 24; in other words, the insertion slot 22 bof the access point device “B” 20 b precedes the insertion slot 22 a ofits successor access point device “A” 20 a, enabling the first accesspoint device “A” 20 a to receive the data packet 14 during its insertionslot 22 a from either the movable network device “J” 16 (if positionednear the access point device 20 a) or its succeeding next-hopneighboring access point device “B” 20 b that successively follows inthe repeatable sequence. Similarly, the insertion slot 22 c of theaccess point device “C” 20 c precedes the insertion slot 22 b of itssuccessor access point device “B” 20 b; the insertion slot 22 d of theaccess point device “D” 20 d precedes the insertion slot 22 c of itssuccessor access point device “C” 20 c; and the insertion slot 22 e ofthe access point device “E” 20 d precedes the insertion slot 22 d of itssuccessor access point device “D” 20 d.

Hence, each insertion slot 22 enables a corresponding access pointdevice 20 to receive the data packet from any one of the movable networkdevice “J” 16 or a succeeding access point of the repeatable sequence ofaccess point devices. As illustrated in FIG. 1, and described in furtherdetail below, the reception of the data packet 14 during the insertionslot 22 d from the movable network device “J” 16 causes the access pointdevice “D” 20 d to forward the data packet 14 to its successor accesspoint device “C” 20 c at the insertion slot 22 c; the reception of thedata packet 14 during the insertion slot 22 c from the access pointdevice “D” 20 d causes the access point device “C” 20 c to forward thedata packet 14 to its successor access point device “B” 20 b at theinsertion slot 22 b; and the reception of the data packet 14 during theinsertion slot 22 b from the access point device “C” 20 c causes theaccess point device “B” 20 b to forward the data packet 14 to itssuccessor access point device “A” 20 a at the insertion slot 22 a.

The deterministic track 12 established by the “dual-entry” insertionslots 22 enables the movable network device “J” 16 to transmit the datapacket 14 to any one of the access point devices 20 in the repeatablesequence of access point devices “E”-“D”-“C”-“B”-“A”, using thecorresponding allocated insertion slot 22, based on the movable networkdevice “J” 16 determining the nearest access point device 20 in therepeatable sequence.

As the movable network device “J” 16 moves along its physical path 18(e.g., at an example speed of 1 meter/second), the movable networkdevice “J” 16 can transmit a first data packet 14 to its nearest accesspoint device “E” 20 e at the insertion slot 22 e, causing the datapacket 14 to be propagated along the deterministic track 12 via theaccess point devices 20 d, 20 c, 20 b, and 20 a at insertion slots 22 d,22 c, 22 b, and 22 a, respectively, within one instance of the CDUmatrix 24: as described below, additional data packets 14 can betransmitted to the nearest access point device “E” 20 e at the insertionslot 22 e during a later instance of the repeating CDU 24.

As the movable network device “J” 16 moves along the physical path 18,the movable network device “J” 16 can transmit (during a subsequentinstance of the CDU matrix 24) a second data packet 14 to its nearestaccess point device “D” 20 d at the insertion slot 22 d as illustratedin FIG. 1, causing the data packet 14 to propagated along thedeterministic track 12 via the access point devices 20 c, 20 b, and 20 aat insertion slots 22 c, 22 b, and 22 a, respectively, within the oneinstance of the CDU matrix 24.

As the movable network device “J” 16 moves along the physical path 18,the movable network device “J” 16 can transmit (during a subsequentinstance of the CDU matrix 24) a third data packet 14 to its nearestaccess point device “C” 20 c at the insertion slot 22 c, causing thedata packet 14 to propagated along the deterministic track 12 via theaccess point devices 20 b and 20 a at insertion slots 22 b and 22 a,respectively, within the one instance of the CDU matrix 24.

As the movable network device “J” 16 moves along the physical path 18,the movable network device “J” 16 can transmit (during a subsequentinstance of the CDU matrix 24) a fourth data packet 14 to its nearestaccess point device “B” 20 b at the insertion slot 22 b, causing thedata packet 14 to propagated along the deterministic track 12 via theaccess point device 20 a at insertion slot 22 a. Similarly, if themovable network device “J” 16 moves along the physical path 18 such thatthe access point device “A” 20 a is the nearest access point device, themovable network device “J” 16 can transmit (during a subsequent instanceof the CDU matrix 24) a fifth data packet 14 to the first access pointdevice “A” 20 a using the insertion slot 22 a.

Hence, each insertion slot 22 enables a corresponding access pointdevice 20 to receive the data packet 14 from any one of the movablenetwork device “J” 16 or a succeeding access point of the repeatablesequence of access point devices. Consequently, the deterministic track12 comprising the insertion slots 22 a, 22 b, 22 c, 22 d, and 22 eenable propagation of the data packet 14 from the movable network device16 to the first access point device “A” 20 a, via at least zero or moreof the access point devices “B” 20 b, “C” 20 c, “D” 20 d, and “E” 20 esuccessively following the first access point device “A” 20 a in therepeatable sequence, depending on the position of the movable networkdevice “J” 16 in the physical path 18 that cause the movable networkdevice “J” 16 to determine the nearest access point device 20.

The first access point device “A” 20 a, in response to receiving thedata packet 14, can forward the data packet 14 to a destination device30 via a deterministic local area network (LAN) 32 using a seconddeterministic track (66 of FIG. 2) between the first access point device“A” 20 a and the destination device 30.

Hence, the example embodiments can preserve deterministic forwarding ofa data packet 14, despite movement of the originating movable networkdevice “J” 16, without the necessity of recalculation of a newdeterministic track by the PCE 28.

FIG. 2 illustrates another example network 10′ for establishing adeterministic track along a repeatable sequence of access point devices20, with insertion slots for insertion of a data packet 14 by a movablenetwork device “J” 16, according to an example embodiment. FIG. 2illustrates that network 10′ can include a wireless RPL network 34comprising the access point devices “A” 20 a, “B” 20 b, and “C” 20 c.The RPL network 34 also comprises a root network device “R” 36, andother RPL network devices 38. The access point device “A” 20 a can reachthe root network device “R” 36 (and the destination device 30) via theRPL network devices “X” and “Y” 38; the access point device “B” 20 b canreach the root network device “R” 36 (and the destination device 30) viathe RPL network devices “L” and “M” 38; and the access point device “C”20 c can reach the root network device “R” 36 (and the destinationdevice 30) via the RPL network device “H” 38.

Hence, the movable network device “J” 16 in FIG. 2 can be a mobilenetwork device moving along a repeatable physical path 18′ within theRPL network 34, resulting in moving along the repeatable sequence ofaccess point devices “A”-“B”-“C” in the RPL network 34.

As described in further detail below with respect to FIGS. 6A, 6B, and6C, the movable network device “J” 16 is configured to establish thedeterministic track (12′ of FIG. 6C) based on requesting insertion slots22 from the respective access point devices 20. In particular, the cells26 in the CDU matrix 24 generated by the PCE 28 can be grouped into“chunks”, where each chunk is exclusively allocated to a correspondingnetwork device 20, 36, or 38 in the RPL network 34; hence, each accesspoint device 20 a, 20 b, and 20 c can allocate its own insertion slot 22from its corresponding allocated chunk for use by the movable networkdevice “J” 16 in transmitting a data packet 14 to the correspondingaccess point device 20.

According to an example embodiment, the movable network device “J” 16can determine it is moving along a repeatable sequence of access pointdevices “A”-“B”-“C”, and in response the movable network device “J” 16can obtain respective insertion slots 22 a, 22 b, and 22 c (in FIGS. 6A,6B, and 6C) that enables formation of a deterministic track 12′ alongthe repeatable sequence of access point devices “A”-“B”-“C”. The movablenetwork device “J” 16 can establish the deterministic track 12′ based onrequesting an insertion slot 22 that precedes a previously-receivedinsertion slot 22 from a successor access point device 20. Hence, themovable network device “J” 16 can dynamically establish thedeterministic track 12′ based on requesting insertion slots 22 relativeto the physical path 18′, which can be detectable based on the movablenetwork device J″ 16 tracking the sequence of access point devices 20detected by the movable network device “J” 16.

FIG. 3 illustrates an example implementation of any one of the devices16, 20, 28, 30, 36, or 38, according to an example embodiment. Eachdevice (i.e., apparatus) 16, 20, 28, 30, 36, or 38 is a physical machine(i.e., a hardware device) configured for implementing networkcommunications with other physical machines via the deterministicnetwork 10 or 10′. The term “configured for” or “configured to” as usedherein with respect to a specified operation refers to a device and/ormachine that is physically constructed and arranged to perform thespecified operation.

Each apparatus 16, 20, 28, 30, 36, or 38 can include a device interfacecircuit 40, a processor circuit 42, and a memory circuit 44. The deviceinterface circuit 40 can include one or more distinct physical layertransceivers for communication with any one of the other devices 16, 20,28, 30, 36, or 38; the device interface circuit 40 also can include anIEEE based Ethernet transceiver for communications with the devices ofFIG. 1 or 2 via any of the data links (e.g., a wired or wireless link,an optical link, etc.). The processor circuit 42 can be configured forexecuting any of the operations described herein, and the memory circuit44 can be configured for storing any data or data packets as describedherein, for example in a data structure 46.

Any of the disclosed circuits of the devices 16, 20, 28, 30, 36, or 38(including the device interface circuit 40, the processor circuit 42,the memory circuit 44, and their associated components) can beimplemented in multiple forms. Example implementations of the disclosedcircuits include hardware logic that is implemented in a logic arraysuch as a programmable logic array (PLA), a field programmable gatearray (FPGA), or by mask programming of integrated circuits such as anapplication-specific integrated circuit (ASIC). Any of these circuitsalso can be implemented using a software-based executable resource thatis executed by a corresponding internal processor circuit such as amicroprocessor circuit (not shown) and implemented using one or moreintegrated circuits, where execution of executable code stored in aninternal memory circuit (e.g., within the memory circuit 44) causes theintegrated circuit(s) implementing the processor circuit to storeapplication state variables in processor memory, creating an executableapplication resource (e.g., an application instance) that performs theoperations of the circuit as described herein. Hence, use of the term“circuit” in this specification refers to both a hardware-based circuitimplemented using one or more integrated circuits and that includeslogic for performing the described operations, or a software-basedcircuit that includes a processor circuit (implemented using one or moreintegrated circuits), the processor circuit including a reserved portionof processor memory for storage of application state data andapplication variables that are modified by execution of the executablecode by the processor circuit. The memory circuit 44 can be implemented,for example, using a non-volatile memory such as a programmable readonly memory (PROM) or an EPROM, and/or a volatile memory such as a DRAM,etc.

Further, any reference to “outputting a message” or “outputting apacket” (or the like) can be implemented based on creating themessage/packet in the form of a data structure and storing that datastructure in a non-transitory tangible memory medium in the disclosedapparatus (e.g., in a transmit buffer). Any reference to “outputting amessage” or “outputting a packet” (or the like) also can includeelectrically transmitting (e.g., via wired electric current or wirelesselectric field, as appropriate) the message/packet stored in thenon-transitory tangible memory medium to another network node via acommunications medium (e.g., a wired or wireless link, as appropriate)(optical transmission also can be used, as appropriate). Similarly, anyreference to “receiving a message” or “receiving a packet” (or the like)can be implemented based on the disclosed apparatus detecting theelectrical (or optical) transmission of the message/packet on thecommunications medium, and storing the detected transmission as a datastructure in a non-transitory tangible memory medium in the disclosedapparatus (e.g., in a receive buffer). Also note that the memory circuit44 can be implemented dynamically by the processor circuit 42, forexample based on memory address assignment and partitioning executed bythe processor circuit 42.

FIG. 4 illustrates an example method of establishing a deterministictrack 12 with insertion slots 22 for insertion of a data packet 14, by amovable network device 16, along a repeatable sequence of access pointdevices 20, according to an example embodiment.

FIG. 5 illustrates in further detail an example method for establishingthe deterministic track 12 along a repeatable sequence of access pointdevices 20, with insertion slots 22 for insertion of a data packet 14 bya movable network device 16, according to an example embodiment.

FIGS. 6A, 6B, and 6C illustrate an example sequence of a movable networkdevice “J” 16 establishing a deterministic track (12′ of FIG. 6C) alongthe repeatable sequence of access point devices 20, based onsuccessively obtaining insertion slots 22 from each of the access pointdevices 20, according to an example embodiment.

The operations described with respect to any of the Figures can beimplemented as executable code stored on a computer or machine readablenon-transitory tangible storage medium (e.g., floppy disk, hard disk,ROM, EEPROM, nonvolatile RAM, CD-ROM, etc.) that are completed based onexecution of the code by a processor circuit implemented using one ormore integrated circuits; the operations described herein also can beimplemented as executable logic that is encoded in one or morenon-transitory tangible media for execution (e.g., programmable logicarrays or devices, field programmable gate arrays, programmable arraylogic, application specific integrated circuits, etc.). Hence, one ormore non-transitory tangible media can be encoded with logic forexecution by a machine, and when executed by the machine operable forthe operations described herein.

In addition, the operations described with respect to any of the Figurescan be performed in any suitable order, or at least some of theoperations in parallel. Execution of the operations as described hereinis by way of illustration only; as such, the operations do notnecessarily need to be executed by the machine-based hardware componentsas described herein; to the contrary, other machine-based hardwarecomponents can be used to execute the disclosed operations in anyappropriate order, or at least some of the operations in parallel.

Referring to FIG. 4, the processor circuit 42 of the PCE 28 and/or themovable network device “J” 16 in operation 50 can determine that themovable network device “J” 16 is moving (or will be moving) along arepeatable sequence of access point devices 20 in the deterministicnetwork 10. For example, the processor circuit 42 of the PCE 28 can beconfigured for determining that the physical path 18 is within wirelessrange of a repeatable sequence of access point devices 20, based ondetecting that the movable network device “J” 16 is following a physicalpath 18: in one example, the movable network device “J” 16 can bemounted on a trolley that moves along a track mounted on a boom (jib) ofa “hammerhead” tower crane at a construction site; hence the PCE 28 canpreprogram the movable network device “J” 16 and each of the accesspoint devices 20 with the associated insertion slots 22 based on thephysical path 18 traversed by the movable network device “J” 16 as thetrolley moves along the track of the boom on the tower crane, and theprocessor circuit 42 of the movable network device “J” 16 can detect thenearest access point device 20 based on linear sensors (and/or GPSsensors) detecting the position of the movable network device “J” 16 onthe physical path 18.

In another example of the movable network device “J” 16 implemented forexample as part of an unmanned aerial vehicle (UAV) such as aquadcopter, the processor circuit 42 of the PCE 28 and/or the movablenetwork device “J” 16 in operation 50 can determine the physical path 18based on a prescribed flight path for the movable network device “J” 16stored in the data structure 46 of the movable network device “J” 16,and/or based solely on tracking a detected telemetry (e.g., GPS tracks)generated by inertial or GPS sensors on the UAV that optionally can bestored locally in the data structure 46 and/or transmitted to the PCE 28via the nearest access point device 20 (e.g., using a cell 26 allocatedby the nearest access point device 20 for initial/ad hoc communicationswith the PCE 28).

The processor circuit 42 of the movable network device “J” 16 and/or thePCE 28 in operation 50 also can determine that the movable networkdevice “J” 16 is moving along a repeatable sequence of access pointdevices 20 based on detecting and tracking the sequence that the movablenetwork device “J” 16 attaches to the access point devices 20. Hence,the repeatable sequence of access point devices 20 can be tracked anddetermined without detection of the physical path 18 or correlation ofthe physical path 18 to the nearest access point devices 20 along thephysical path 18.

The processor circuit 42 of the movable network device “J” 16 and/or thePCE 28 in operation 52 can establish the deterministic track 12 alongthe repeatable sequence of access point devices 20, where thedeterministic track 12 comprises the insertion slots 22 that enable themovable network device “J” 16 to insert a data packet 14 into thedeterministic track 12 (or 12′ of FIG. 6C) via any one of the respectiveaccess point devices 20. For example, the PCE 28 can send a 6TiSCHschedule to the access point devices 20 and the movable network device“J” 16, optionally with a “dual-entry” insertion slot option. Hence, themovable network device “J” 16 can obtain from the PCE 28 each of theinsertion slots 22 for transmitting the data packet 14 into thedeterministic track 12 via any one of the access point devices 20.Similarly, each of the access point devices 20 along the repeatablesequence (e.g., “E”-“D”-“C”-“B”-“A” of FIG. 1 or “A”-“B”-“C” of FIGS.6A-6C) can be preprogrammed with the corresponding insertion slot 22allocated exclusively for reception of the data packet 14 originated bythe movable network device “J” 16, enabling each access point device 20to identify the corresponding insertion slot 22 allocated exclusivelyfor reception of the data packet 14; at least the succeeding accesspoint devices 20 (e.g., “E”-“D”-“C”-“B” in FIG. 1 or “B”-“C” in FIGS.6A-6C) succeeding the origin access point device “A” 20 a also canreceive an identification of the second corresponding insertion slot 22reserved exclusively for transmitting the data packet 14 to itssuccessor access point device 20.

Hence, reception of the first and second insertion slots 22 from the PCE28 enables each access point device 20 to deterministically receive thedata packet 14 from either the movable network device “J” 16 or asucceeding access point device 20 using its first correspondinginsertion slot 22, and deterministically forward the data packet 14 toits corresponding successor access point device 20 using the secondcorresponding insertion slot 22. Any one of the access point devices 20also can be implemented as a switching device providing the necessarytiming and/or synchronization intervals to received and/or transmitteddata packets as described with respect to the insertion slots.

As described in further detail below with respect to FIG. 5 and FIGS.6A-6C, the processor circuit 42 of the movable network device “J” 16 inoperation 52 also can establish the deterministic track 12′ dynamicallywith the access point devices 20 based on the processor circuit 42 ofthe movable network device “J” 16 dynamically requesting the insertionslots 22 from the respective access point device 20 as the movablenetwork device “J” 16 moves along its physical path 18′. As describedpreviously, each access point device 20 can acquire from the PCE 28 acorresponding unique chunk comprising a plurality of unique cells 26;hence, the processor circuit 42 of each access point device 20 canrespond to the corresponding request from the movable network device “J”16 by allocating an insertion slot 22 (associated with a correspondingcell 26) from its corresponding chunk having been acquired from the PCE28.

The processor circuit 42 of the movable network device “J” 16 inoperation 54 determines the nearest access point device 20 as themovable network device “J” 16 moves along the repeatable sequence ofaccess point devices 20, for example based on a position sensor locallyassociated with the movable network device “J” 16 relative to storedidentification of the access point devices 20 along the physical path18, a comparison of received signal strength indicators (RSSIs) betweentwo adjacent access point devices 20 providing overlapping wirelesspropagation areas, etc. In response to the processor circuit 42 of themovable network device “J” 16 determining the closest access pointdevice (e.g., 20 b), the processor circuit 42 of the movable networkdevice “J” 16 in operation 56 causes the device interface circuit 40 totransmit the data packet 14 to the nearest access point device 20 basedon selecting the insertion slot (e.g., 22 b) associated with the nearestaccess point device (e.g., 20 b) from among the insertion slots 22associated with the respective access point devices 20 of the physicalpath 18 or 18′.

The device interface circuit 40 of the nearest access point device(e.g., 20 b) in operation 58 receives the data packet 14 from themovable network device “J” 16 during the insertion slot (e.g., 22 b)allocated for transmission to the access device (e.g., 20 b) from themovable network device “J” 16 (or a succeeding access point device 20 c,described below). If in operation 60 the access point device (e.g., 20b) is not an origin access point “A” as described above (i.e., the firstaccess point at the end of the deterministic track 12 or 12′), theprocessor circuit 42 of the succeeding access point device (e.g., 20 b)accesses its forwarding table in the data structure 46 stored in thememory circuit 44 to determine that the data packet 14 received on thereceiving insertion slot (e.g., 22 b) is to be transmitted to itssuccessor access point device (e.g., 20 a) on the transmitting insertionslot (e.g., 22 a). Hence, each succeeding access point device 20 caninclude one or more table entries in its corresponding data structure 46specifying at least a transmitting insertion slot for each receivinginsertion slot 22 for a given deterministic track 12 or 12′.

Hence, the succeeding access point device (e.g., 20 b) in operation 62deterministically forwards the data packet 14, received during theinsertion slot 22 b, to its successor access point device (e.g., 20 a)at the corresponding transmitting insertion slot (e.g., 22 a), enablingdeterministic transmission of the data packet 14 along the deterministictrack 12 or 12′. As apparent from FIG. 4, operations 58 and 62 can beexecuted by each access point device 20 along the repeatable sequence ofaccess point devices 20 until the data packet 14 reaches the originaccess point device “A” 20 a.

In response to the access point device 20 a receiving the data packet 14at the insertion slot 22 a in operation 58, the processor circuit 42 ofthe access point device 20 a can determine that it is the origin accesspoint for the deterministic track 12, and in response forward inoperation 64 the data packet 14 to the destination (e.g., 30 of FIG. 2via the root network device “R” 36) using a cell 26 having beenallocated by a parent network device (e.g., “X” 38 of FIG. 2) providingreachability to the access point device 20 a. As described previously,the access point device 20 a (and network devices “X” 38, “Y” 38, and“R” 36 of FIG. 2) can be part of a second deterministic track 66allocated by the PCE 28.

Hence, the example embodiments enable a deterministic track 12 or 12′ tobe established along the repeatable sequence of access point devices 20,where the deterministic track 12 includes insertion slots 22 allocatedfor insertion of a data packet 14, by the movable network device “J” 16,into the deterministic track 12 via any one of the access point devices20. Each insertion slot 22 enables a corresponding access point device20 to receive the data packet 14 from either the movable network device“J” 16 or a succeeding access point 20 in the repeatable sequence. Thedeterministic track 12 or 12′ is within a single instance of therepeating cell 26, enabling propagation of the data packet 14 from themovable network device “J” 16 to the origin access point device “A” 20 avia at least zero or more of the access point devices “B” 20 b, “C” 20c, etc., successively following the origin access point device “A” 20 ain the repeatable sequence.

Hence, the example embodiments enable deterministic forwarding of thedata packet 14 in the deterministic network 10, even though the movablenetwork device “J” 16 moves among different access point devices 20,based on the establishment of the deterministic track 12.

FIG. 5 illustrates in further detail the movable network device “J” 16establishing the deterministic track 12′ of FIGS. 6A, 6B, and 6C(summarized in operation 52 of FIG. 4), according to an exampleembodiment. The operations of FIG. 5 also can be applied to establishingthe deterministic track 12 in the example of FIG. 1 if the direction ofphysical path 18 was reversed to match the physical path 18′ of FIGS.6A-6C, in other words the movable network device “J” 16 started with theorigin access point device “A” 20 a and successively establishedwireless connections with the sequence of access point devices “B” 20 b,“C” 20 c, “D” 20 d, and “E” 20 e.

Referring to operation 70, the processor circuit 42 of the movablenetwork device “J” 16 can request an insertion slot 22 from the originaccess point device “A” 20 a, causing the processor circuit 42 of theorigin access point device “A” 20 a to allocate the first insertion slot“A_J” 22 a to the movable network device “J” 16 as illustrated in FIG.6A. As described previously, the origin access point device “A” 20 a canallocate the first insertion slot “A_J” 22 a from a chunk “A” havingbeen allocated to the origin access point device “A” 20 a. Hence, themovable network device “J” 16 can transmit a data packet 14 to theorigin access point device “A” 20 a using first insertion slot “A_J” 22a, illustrated in FIG. 6A by the solid arrow between the movable networkdevice “J” 16 and the origin access point device “A” 20 a (dashed linesrefer to unused links in the deterministic track 12 for the specificinstance of the CDU matrix 24).

The movable network device “J” 16 in operation 72 moves along thephysical path 18′ and detects the second access point device “B” 20 bsucceeding the origin access point device “A” 20 a. In response todetecting the second access point device “B” 20 b, the processor circuit42 of the movable network device “J” 16 is configured for requesting inoperation 72 an insertion slot 22 that precedes the insertion slot “A_J”22 a; for example, the request sent by the movable network device “J” 16to the access point device 20 b can specify the insertion slot “A_J” 22a received from the successor access point device “A” 20 a.

In response to the second access point device “B” 20 b in operation 74receiving the request for an insertion slot 22 that precedes theinsertion slot “A_J” 22 a, the second access point device “B” 20 b canidentify that the insertion slot “A_J” 22 a is allocated exclusively fortransmitting any data packet 14 originated by the movable network device“J” 16 to the successor access point device “A” 20 a. Hence, the secondaccess point device “B” 20 b can respond to the request by allocating(from its allocated chunk “B”) a second insertion slot “B_J” 22 b thatprecedes the insertion slot “A_J” 22 a, and creating a table entry inits data structure 46 that associates the second insertion slot “B_J” 22b with the first insertion slot “A_J” 22 a.

The movable network device “J” 16 receives in operation 76 the secondinsertion slot “B_J” 22 b for transmitting a data packet 14 to the nextsuccessive access point device “B” 20 b. Hence, as illustrated in FIG.6B by the solid arrows, any data packet 14 received by the second accesspoint “B” 20 b on the second insertion slot “B_J” 22 b is forwarded bythe second access point “B” 20 b to the origin access point device “A”20 a using the first insertion slot “A_J” 22 a (illustrated in FIG. 6B).If in operation 78 the movable network device “J” 16 determines it isnot at the end of the determined repeatable sequence of access pointdevices 20, the movable network device “J” 16 can continue addinginsertion slots 22 from successive access point devices (e.g., “C” 20 c)until the deterministic track 12 along the entire sequence of accesspoint devices 20 has been completed in operation 80.

As illustrated in FIG. 6C, operations 72, 75, and 76 can be completedfor the next successive access point device “C” 20 c based on themovable network device “J” 16 in operation 62 requesting an insertionslot 22 that precedes the second insertion slot “B_J” 22 b. Thesuccessive access point device “C” 20 c in operation 74 can respond tothe received request by allocating to the movable network device “J” 16a third insertion slot “C_J” 22 c that precedes the second insertionslot “B_J” 22 b, and storing a forwarding table entry in the datastructure 46 specifying that any data packet 14 received by the accesspoint device “C” 20 c on the third insertion slot “C_J” 22 c isforwarded on the second insertion slot “B_J” 22 b to its successoraccess point device “B” 20 b.

Hence, the movable network device “J” 16 is able to establish thedeterministic track 12′ comprising the insertion slots “C_J” 22 c, “B_J”22 b, and the “A_J” 22 a, enabling the device interface circuit 40 ofthe movable network device “J” 16 to transmit the data packet 14 to thenearest access point device 20 using the corresponding selectedinsertion slot 22, for deterministic forwarding of the data packet 14within the sequence of access point devices 20 via the deterministictrack 12′. Further, the movable network device “J” 16 is able toidentify to each successive access point device (e.g., “B” 20 b or “C”20 c) the insertion slot (e.g., “A_J” 22 a or “B_J” 22 b) of thecorresponding successor access point device (e.g., “A” 20 a or “B” 20b), enabling the corresponding successive access point device (e.g., “B”20 b or “C” 20 c) to deterministically forward the data packet 14 to itssuccessor access point device (e.g., “A” 20 a or “B” 20 b), without thenecessity of additional allocation of any insertion slot 22 by thesuccessor access point device. In other words, the successive accesspoint device (e.g., “B” 20 b or “C” 20 c) acts as a “proxy” intransmitting the data packet 14 on behalf of the movable network device“J” 16 during the insertion slot (e.g., “A_J” 22 a or “B_J” 22 b)associated with the corresponding successor access point device (e.g.,“A” 20 a or “B” 20 b).

Also note with respect that the physical path 18′ of FIGS. 6A, 6B, and6C illustrate that the repeatable sequence of access point devices 20can be applied in a “circular” pattern (e.g., “A”-“B”-“C”-“B”-“A”,etc.), hence, FIG. 6C illustrates that the movable network device “J” 16has a transmit opportunity on the insertion slot “B_J” 22 b on the“outward” trajectory (i.e., moving away from the origin access pointdevice “A” 20 a and toward the access point device “C” 20 c) and anothertransmit opportunity on the insertion slot “B_J” 22 b on the “inward” or“return” trajectory (i.e., moving toward the origin access point device“A” 20 a and away from the access point device “C” 20 c) of the physicalpath 18. As illustrated in FIG. 6C, the movable network device “J” 16can have multiple (e.g., three or more) transmit opportunities on anygiven insertion slot (e.g., 22 c) over multiple instances of the CDUmatrix 24, since the duration of communications with a given accesspoint device 20 can span multiple instances of the CDU matrix 24 due tothe relative speed of the movable network device “J” 16 on the physicalpath 18 relative to the duration of the repeatable CDU matrix 24.

According to example embodiments, a deterministic track can beestablished for a movable network device that enables deterministicforwarding of data packets as the movable network device movesthroughout a deterministic network, eliminating any need forrecalculating replacement deterministic tracks or topology updates dueto the movable network device detaching from an existing access pointdevice and attaching to different access point devices. Thedeterministic track can be appended to another deterministic track thatterminates at an origin access point of the movable network device,enabling the movable network device to maintain deterministictransmission of data packets as it moves throughout the deterministicnetwork.

While the example embodiments in the present disclosure have beendescribed in connection with what is presently considered to be the bestmode for carrying out the subject matter specified in the appendedclaims, it is to be understood that the example embodiments are onlyillustrative, and are not to restrict the subject matter specified inthe appended claims.

What is claimed is:
 1. A method comprising: a deterministic networkaccess device in a deterministic network receiving identification of afirst insertion slot allocated exclusively for transmission of a datapacket originated by a movable network device to a successordeterministic network access device, the deterministic network accessdevice and the successor deterministic network access device belongingto a repeatable sequence of deterministic network access devicesfollowed by the movable network device as the movable network devicemoves in the deterministic network; the deterministic network accessdevice identifying a second insertion slot allocated to the movablenetwork device and preceding the first insertion slot; the deterministicnetwork access device receiving, during the second insertion slot, adata packet originated by the movable network device; and thedeterministic network access device deterministically forwarding thedata packet, received during the second insertion slot, to the successordeterministic network access device at the first insertion slot, thesecond insertion slot preceding the first insertion slot being part of adeterministic track established for deterministic forwarding of the datapacket along the sequence of deterministic network access devices. 2.The method of claim 1, wherein: the second insertion slot is a dualentry slot that enables the deterministic network access device toreceive the data packet from any one of movable network device or asucceeding deterministic network access device belonging to therepeatable sequence; the first insertion slot a dual entry slot thatenables the deterministic network access device to deterministicallyforward the data packet to the successor deterministic network accessdevice without allocation of the first insertion slot by the successordeterministic network access device or any path computation element tothe deterministic network access device.
 3. The method of claim 1,wherein each insertion slot corresponds to a unique transmission channelat a unique timeslot.
 4. The method of claim 1, wherein thedeterministic network access device is implemented as any one of awireless access device, a wired access device, or an optical accessdevice.
 5. The method of claim 1, wherein: the receiving identificationof the first insertion slot includes the deterministic network accessdevice receiving, from the movable network device, a request for aninsertion slot preceding the first insertion slot specified in therequest; the method further comprising the deterministic network accessdevice creating a table entry associating the second insertion slot withthe first insertion slot, and responding to the request withidentification of the second insertion slot.
 6. The method of claim 1,wherein the deterministic network access device and the successordeterministic network access device are attached to distinct parentnetwork devices in a tree-based topology.
 7. An apparatus comprising: adevice interface circuit configured for receiving, in a deterministicnetwork, identification of a first insertion slot allocated exclusivelyfor transmission of a data packet originated by a movable network deviceto a successor deterministic network access device, the apparatusimplemented as a deterministic network access device in thedeterministic network, the deterministic network access device and thesuccessor deterministic network access device belonging to a repeatablesequence of deterministic network access devices followed by the movablenetwork device as the movable network device moves in the deterministicnetwork; and a processor circuit configured for identifying a secondinsertion slot allocated to the movable network device and preceding thefirst insertion slot; the device interface circuit configured forreceiving, during the second insertion slot, a data packet originated bythe movable network device; the device interface circuit configured fordeterministically forwarding the data packet, received during the secondinsertion slot, to the successor deterministic network access device atthe first insertion slot, the second insertion slot preceding the firstinsertion slot being part of a deterministic track established fordeterministic forwarding of the data packet along the sequence ofdeterministic network access devices.
 8. The apparatus of claim 7,wherein the second insertion slot is a dual entry slot that enables thedeterministic network access device to receive the data packet from anyone of movable network device or a succeeding deterministic networkaccess device belonging to the repeatable sequence; the first insertionslot a dual entry slot that enables the deterministic network accessdevice to deterministically forward the data packet to the successordeterministic network access device without allocation of the firstinsertion slot by the successor deterministic network access device orany path computation element to the deterministic network access device.9. The apparatus of claim 7, wherein each insertion slot corresponds toa unique transmission channel at a unique timeslot.
 10. The apparatus ofclaim 7, wherein deterministic network access device is implemented asany one of a wireless access device, a wired access device, or anoptical access device.
 11. The apparatus of claim 7, wherein: the deviceinterface circuit is configured for receiving, from the movable networkdevice, a request for an insertion slot preceding the first insertionslot specified in the request; the processor circuit configured forcreating a table entry associating the second insertion slot with thefirst insertion slot, and responding to the request with identificationof the second insertion slot.
 12. The apparatus of claim 7, wherein theapparatus and the successor deterministic network access device areattached to distinct parent network devices in a tree-based topology.13. One or more non-transitory tangible media encoded with logic forexecution by a machine and when executed by the machine operable for:the machine, implemented as a deterministic network access device in adeterministic network, receiving identification of a first insertionslot allocated exclusively for transmission of a data packet originatedby a movable network device to a successor deterministic network accessdevice, the deterministic network access device and the successordeterministic network access device belonging to a repeatable sequenceof deterministic network access devices followed by the movable networkdevice as the movable network device moves in the deterministic network;the deterministic network access device identifying a second insertionslot allocated to the movable network device and preceding the firstinsertion slot; the deterministic network access device receiving,during the second insertion slot, a data packet originated by themovable network device; and the deterministic network access devicedeterministically forwarding the data packet, received during the secondinsertion slot, to the successor deterministic network access device atthe first insertion slot, the second insertion slot preceding the firstinsertion slot being part of a deterministic track established fordeterministic forwarding of the data packet along the sequence ofdeterministic network access devices.
 14. The one or more non-transitorytangible media of claim 13, wherein: the second insertion slot is a dualentry slot that enables the deterministic network access device toreceive the data packet from any one of movable network device or asucceeding deterministic network access device belonging to therepeatable sequence; the first insertion slot a dual entry slot thatenables the deterministic network access device to deterministicallyforward the data packet to the successor deterministic network accessdevice without allocation of the first insertion slot by the successordeterministic network access device or any path computation element tothe deterministic network access device.
 15. The one or morenon-transitory tangible media of claim 13, wherein each insertion slotcorresponds to a unique transmission channel at a unique timeslot. 16.The one or more non-transitory tangible media of claim 13, wherein thedeterministic network access device is implemented as any one of awireless access device, a wired access device, or an optical accessdevice.
 17. The one or more non-transitory tangible media of claim 13,wherein: the receiving identification of the first insertion slotincludes the deterministic network access device receiving, from themovable network device, a request for an insertion slot preceding thefirst insertion slot specified in the request; the one or morenon-transitory tangible media further operable for the deterministicnetwork access device creating a table entry associating the secondinsertion slot with the first insertion slot, and responding to therequest with identification of the second insertion slot.
 18. The one ormore non-transitory tangible media of claim 13, wherein thedeterministic network access device and the successor deterministicnetwork access device are attached to distinct parent network devices ina tree-based topology.